Explicitly disable not used ckeditor plugins

All of these plugins are not used anywhere.

Change introduced at ckeditor initializer will ommit unneeded
precompilation of plugins assets on production environments.

Change introduced at ckeditor config file adresses the problem with assets
pipeline fallback on testing environments described here: #2711. Now plugins
that are explicitly disabled will not be precomiled when running ckeditor
javascript enabled feature specs.

app/assets/javascripts/ckeditor/config.js

@@ -14,6 +14,8 @@ CKEDITOR.editorConfig = function( config )
   config.allowedContent = true;
   config.format_tags = "p;h2;h3";
 
+  config.removePlugins = "balloonpanel,balloontoolbar,copyformatting,scayt,wsc";
+
   // Rails CSRF token
   config.filebrowserParams = function(){
     var csrf_token, csrf_param, meta,

config/initializers/ckeditor.rb

@@ -8,7 +8,7 @@ Ckeditor.setup do |config|
   config.authorize_with :cancan
 
   config.assets_languages = Rails.application.config.i18n.available_locales.map { |l| l.to_s.downcase }
-  config.assets_plugins = %w[balloonpanel balloontoolbar copyformatting image
-                             link magicline pastefromword scayt table tableselection wsc]
+  config.assets_plugins = %w[image link magicline pastefromword
+                             table tableselection]
   config.assets.reject! { |asset| asset =~ /\Ackeditor\/samples\// }
 end